A standards body of mobile communication methods, 3GPP, has recently been deliberating about LTE (Long Term Evolution). In the LTE, a frequency band of a system is divided into a plurality of resource blocks (RB), each of which includes one or more (for example, 12) subcarriers. In the LTE, assignment of resource block to a mobile station is performed in every subframe of 1 ms.
As shown in FIG. 4, a communication frame of LTE applicable to TDD consists of 10 subframes. The subframes are categorized into UL subframe available for uplink communication from the mobile station to the base station, DL subframe available for downlink communication from the base station to the mobile station, and special subframe having both a UL region (data reception region) available for the uplink communication and a DL region (data transmission region) available for the downlink communication. FIG. 5 is a diagram illustrating an exemplary symbol arrangement in the special subframe. As shown in FIG. 5, the top 9 symbols in the special subframe are the DL region for the downlink communication and the last 2 symbols across 3 symbols of a guard time are the UL region for the uplink communication. Various configurations of the special subframe, not limited to the symbol arrangement of the FIG. 5, are defined as shown in a table in FIG. 6.
Communications between the base station and a mobile station are performed using the subframes of 3 types described above. For example, physical channels such as PDCCH (Physical Downlink Control Channel), PDSCH (Physical Downlink Shared Channel) and the like are mapped on the DL subframes for the downlink communication. Among them, the PDSCH is used for transmission of user data separately transmitted to each mobile station and control information such as paging information and SIB (System Information Block) transmitted simultaneously to nearby mobile stations. In contrast, the UL subframe for the uplink communication is used for transmission of user data from each mobile station to the base station and control information such as random access from the nearby mobile stations to the base station on the physical channels such as PRACH (Physical Random Access Channel) and the like (for example, see 3GPP TS 36.211 (V8.7.0), “Physical Channels and Modulation”, May 2009).